Trying to setup my FC for the track. (220rwhp)

What size slicks fit under stock fenders with coilovers?

What width and offset 15" wheel would work best?

Thanks!

 

I run 215/580-15 Hoosier slicks on wheels with a 35mm offset and 25mm offset, and both fit. The 25mm offset requires rolling the fenders, where the 35mm sits in there with plenty of space between the front coilover and fender (my front coilovers are inserts in the stock struct body with 2.5" springs).

I haven't tried to fit the 245/580-15 Hoosier slicks, but I'm positive they won't fit with 25mm offset wheels, and probably won't fit on 35mm offset wheels.

 

Awesome! This is the exact response I was waiting on. What width wheel are you using?

What brand and model wheel?

Any pics on the car?

Thank you!!!

 

15x7 on both sets of wheels.

The 35mm are Team Dynamics Pro 1.2 wheels, and the others are Keizer aluminum wheels. Digging for more info, however, I realized that my original information isn't right. I got confused because my Keizers were originally 15x8 that I rebuilt as 15x7 when I changed racing classes...and I use spacers on the Team Dynamics wheels. So here is the correct information...

I run 3/8" spacers on 35mm offset Team Dynamics 15x7 wheels to get the tires to clear the 2.5" diameter springs on the front struts (10" long springs) -- so the truth is that 215/580-15 Hoosier radial slicks on 35mm 15x7 wheels don't clear coilovers utilizing a 2.5" spring. Rather, you need about 25mm offset. My Keizers now have a 3.75" backspacing (I just measured), and those require no spacers and they come right to the edge of the rolled fender with plenty of clearance to the coilover. According to a converter I found online, that means the keizers have a -6mm offset:



This is the Team Dynamics with the 3/8" (roughly 9.5mm) spacers:



What this tells me is that a 15x7 wheel with an offset between -6mm and 25mm will allow 215/580-15 Hoosier slicks to clear a coilover using a 2.5" diameter, 10" long spring.

If you want to get the 245/580-15 slick to clear, probably 20-25mm offset wheels are your best bet...but I doubt they'll fit. To go that wide, I think you'll have to go to widebody front fender to make it work.

 

[QUOTE="Prof. Chaos;11732942"]15x7 on both sets of wheels. /QUOTE]



Because my car won't be an EP car, I was thinking to run 8" wheels for easy sourcing.

What offset and back spacing would you recommend then?

 

The standard on ITS cars is a 15x7, class spec, with a 225/45 or 225/50. You need a wheel/spacer combo to give you a 27mm offset.

 

When my Keizers were 15x8, they had 5.25" backspace (according to an online converter, that's 19mm offset). Hoosier 225/45-15 R compound tires cleared the coilover...but barely. The tire would shift a little at speed, and after each race there'd be scuffs on the springs. The tires always looked fine, so I raced a season that way with no issues.

The Hoosier 225/45-15 R compound is a lot wider than the 215/580-15 slick, so the narrow slick should fit just fine. The 245/580-15 Hoosier certainly wont fit.